The 1977 law made Florida the only US state to ban gay adoption, despite permitting gays and lesbians to foster children.

Yesterday, the court upheld a 2008 ruling by a Miami-Dade judge who approved the adoption of two young brothers by Martin Gill and his male partner.

The boys were neglected by their biological parents and were placed with Mr Gill and his partner in 2004.

Writing on behalf of the three judges on the appeal court panel, Judge Gerald Cope pointed out the disparity of allowing gays and lesbians to foster but not adopt children.

"It is difficult to see any rational basis in utilising homosexual persons as foster parents or guardians on a temporary or permanent basis, while imposing a blanket prohibition on those same persons," he wrote.

"All other persons are eligible to be considered case-by-case to be adoptive parents."

Gay rights campaigners in Florida have warned that gay adoption opponents may seek to place a measure in the state constitution barring gay people from adopting.

Speaking after the ruling, Mr Gill said: “This is just the news that we have been waiting so anxiously for here.

“This is a giant step toward being able to give our sons the stability and permanency that they are being denied.”

Leslie Cooper, a senior staff attorney from the American Civil Liberties Union, which supported Mr Gill, said: “Florida’s law unconstitutionally singles out gay people and the children in their care for unequal treatment, denying many children the long-term security that comes with adoption.

"We are grateful that the court saw the cruel consequences this law has on children, especially those in foster care who may never know the security of a permanent home.”